PADI's AOW manual from the early eighties is 234 pages long. The first quarter of it goes into dive physics and biology in greater depth than OW. There is nav, but it includes natural navigation, not just compass. There's limited visibility and night diving. There's search and there's boat and there's deep diving. And it's ALL the class; there isn't any picking and choosing.
What I'm saying is, analogize to school: you take your general education classes that give you a broad understanding, and then you pick your electives. AOW used to be enhancement of the basics. Now it's electives, and those can be things like fish ID or fiddling with your GoPro. I'm not a SCUBA expert. By I am an expert student, and I know which version of the course--the old way or the new way--taught me more things that will keep me alive.
Specialties can wait until after Rescue Diver. Basics, then expand. (This obviously assumes that OW by itself is too basic to really cover the basics.)
PW